JEE Main 2023 · 25 January · evening · Single correct · +4 / −1
Given below are two statements :
Statement I : In froth floatation method of rotating paddle agitates the mixture to drive air out of it.
Statement II : Iron pyrites and generally avoided for extraction of iron due to environmental reasons.
In the light of the above statements, choose the correct answer from the options given below :
- (a) Statement I is true but Statement II is false
- (b) Statement I is false but Statement II is true
- (c) Both Statement I and Statement II are true
- (d) Both Statement I and Statement II are false
Answer and solution
Answer (b) Statement I is false but Statement II is true
Solution
Chemistry ma’am · 4 steps
Froth flotation needs froth, and froth is air bubbles. The paddle pulls air in, it does not push it out.
- How froth flotation works. Powdered sulphide ore is mixed with water, a collector (pine oil) and a froth stabiliser. A rotating paddle stirs the mixture and draws air into it, which makes a froth.
- Statement I. The ore particles, wetted by the oil, stick to the air bubbles and rise with the froth. The gangue, wetted by water, sinks. Driving air out would destroy the froth, so Statement I is false.
- Statement II. Iron pyrites is FeS₂. Roasting it releases large amounts of SO₂, which pollutes the air and causes acid rain. So iron is extracted from oxide ores such as haematite, Fe₂O₃, and Statement II is true.
- So. Statement I is false and Statement II is true, which is option (b).
The idea to keep. In froth flotation the paddle brings air in to make the froth. Sulphide ores like FeS₂ are avoided for iron because roasting them releases polluting SO₂.
Answer from the NTA final answer key. Solution by PrepWiser.